The only time I usually run out of MP is in like a dungeon and im keeping both dps alive (fast > riot). Other then that sometimes on rdm if im not careful with using my lucid dreaming and i have to rez a lot, I think MP is good to keep red mage from being able to spam rez so much, it's already really powerful.

I'd kind of like specifically on Paladin for clemency to become a high cost MP ability (3000-4000 depending on what works) but OGCD, so you could maximise your mp use but spamming it badly will lock you out of magic attacks (Obviously nerfing sustain especially magic combo, for the sake of healers actually having to heal, but that's another topic) With Dark Knight and Black mage MP a big part of their kit as well so I don't think they would ever get rid of MP, I actually wouldn't mind more MP management but I don't think it's a big issue.

I think MP has a lot of room to be explored with certain jobs (like my PLD "idea"), I also just think it still serves a purpose right now, so I don't see any "endangerment"